# polls.karbach.digital Track Record

> polls.karbach.digital Track Record is a paid API for AI agents from api.polls.karbach.digital, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-28).

Returns the validated backtesting track record of a German election Monte-Carlo forecast model, including MAE, winner accuracy, and per-election results calibrated against 34 historical elections.

## Facts

- Endpoint: GET https://api.polls.karbach.digital/v1/track-record?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-28
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/polls-karbach-digital-track-record-9af41ece
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_rdsPHB5H9U26GCy5YkQTm

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability polls-karbach-digital-track-record-9af41ece
```

Example prompt: Pull the track record for the Karbach German election Monte-Carlo model — I want to see its historical MAE, how often it picks the correct winner, and the 95% confidence interval hit rate across the 34 backtested elections.

## When to prefer this

Use this endpoint when you need to assess the credibility and historical accuracy of the Karbach German election Monte-Carlo model before relying on its forecasts, or when you need to cite validated model performance metrics (MAE, Brier, CI hit rate) in a political analysis context. Prefer it over raw forecast endpoints when the question is about model quality rather than a specific upcoming election.

## Known failure modes

- HTTP 402 if payment header is missing or malformed (x402 micropayment required)
- Stale data if the 6-hour update cycle hasn't completed yet
- Empty elections_2026 array if no 2026 elections have concluded yet
- Network timeout if the API server is temporarily unavailable

## How this service works

Frozen forecasts versus official results, 2026 out of sample and 34-election backtest. Use when asked how reliable these forecasts were in past elections. Source-attributed, German data, updated every six hours.

## Output

A JSON object containing: a backtest summary over 34 historical German elections (MAE ~1.27, Brier score, 95% CI hit rate, winner accuracy), a 2026 election summary with per-election frozen forecasts versus official results, methodology description, data source attribution (dawum.de, ODbL 1.0), and a last-updated timestamp. Forecasts are frozen 8 days before each election and compared against official results.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {
   "description": "Forecasts frozen eight days before the election, measured against official results.",
   "summary_2026": {
    "mae": 2.17,
    "slots": 21,
    "sieger": 3,
    "wahlen": 3,
    "im_band": 17
   },
   "elections_2026": [
    {
     "eid": "st-2026",
     "mae": 2.47,
     "date": "2026-09-06",
     "name": "Landtagswahl Sachsen-Anhalt",
     "actual": {
      "AfD": 43.8,
      "BSW": 5.3,
      "CDU": 17.2,
      "FDP": 2.6,
      "SPD": 9.3,
      "Linke": 8.6,
      "Grüne": 8.9
     },
     "im_band": 5,
     "parteien": 7,
     "v4_frozen": {
      "AfD": 42.3,
      "BSW": 4.1,
      "CDU": 22.1,
      "FDP": 3.3,
      "SPD": 7.3,
      "Linke": 12,
      "Grüne": 5.3
     },
     "frozen_date": "2026-08-28",
     "sieger_stimmt": true
    },
    {
     "eid": "be-2026",
     "mae": 1.74,
     "date": "2026-09-20",
     "name": "Abgeordnetenhaus Berlin",
     "actual": {
      "AfD": 16.3,
      "BSW": 4.7,
      "CDU": 18.8,
      "FDP": 2.5,
      "SPD": 12.1,
      "Linke": 25.7,
      "Grüne": 14.3
     },
     "im_band": 7,
     "parteien": 7,
     "v4_frozen": {
      "AfD": 18,
      "BSW": 3.8,
      "CDU": 19.9,
      "FDP": 3.3,
      "SPD": 12.5,
      "Linke": 20.2,
      "Grüne": 16.1
     },
     "frozen_date": "2026-09-11",
     "sieger_stimmt": true
    }
   ],
   "backtest_34_elections": {
    "mae": 1.27,
    "brier": 0.0711,
    "ci95_hit": 96.9,
    "n_wahlen": 34,
    "updated_at": "2026-10-18 04:30:24",
    "methodology": "v4.16 — punkt=weighted-poll-avg-fenster5 (CLR-sim nur fuer verteilung/CI/sitze/koalitionen; ablation A6/A7 2026-06-10) + per-partei-sigma + party-correlation...",
    "winner_total": 34,
    "winner_correct": 31,
    "baseline_poll_avg_5_mae": {
     "n": 34,
     "mean_mae": 1.3
    }
   }
  },
  "docs": "https://api.polls.karbach.digital/v1/",
  "model": null,
  "notice": "Scenario analysis based on published opinion polls. Not a prediction and not a voting recommendation. Coalitions are arithmetic majorities only, not statemen...",
  "source": {
   "polls": "dawum.de",
   "processing": "polls.karbach.digital (Max Karbach)",
   "polls_license": "ODbL 1.0",
   "polls_license_url": "https://opendatacommons.org/licenses/odbl/1-0/"
  },
  "project": "Ein Projekt von Karbach.Digital (https://karbach.digital)",
  "updated_at": "2026-10-18",
  "uncertainty": null
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/polls-karbach-digital-track-record-9af41ece/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.polls.karbach.digital](https://www.zero.xyz/host/api.polls.karbach.digital/llms.txt)